Trastuzumab Rezetecan Followed by Pyrotinib, and Trastuzumab Combined With Capecitabine as First-line Treatment for Advanced HER2-positive Breast Cancer

This study is a single-arm, exploratory clinical trial, aiming to include patients with HER2-positive advanced breast cancer. It intends to explore the efficacy and safety of trastuzumab combined with pyrotinib, capecitabine ± endocrine therapy as a first-line maintenance treatment for HER2+ advanced breast cancer after induction therapy with rucaparib trastuzumab. After the subjects meet the screening criteria and are enrolled, they receive induction therapy with rucaparib trastuzumab. Among them, patients without disease progression enter the maintenance treatment period and receive trastuzumab combined with pyrotinib, capecitabine ± endocrine therapy (±OFS) for treatment. Until disease progression, or toxicity becomes intolerable, or withdrawal of informed consent, or the investigator determines that the medication must be discontinued. During the study period, imaging evaluations are conducted according to the RECIST 1.1 standard, and the center assessment results are the final results. During the study period, the efficacy indicators such as PFS, ORR, DOR, CBR, and safety indicators of the subjects are evaluated according to the established trial standards, and statistical descriptions are conducted.